1. Field of Related Art
The present invention relates to a sheet receiving apparatus used for stacking or temporarily placing sheets, on which images are formed, ejected from an image forming apparatus, such as a copier and printer.
Particularly, the invention relates to a sheet receiving apparatus, in which sheets ejected sequentially are stacked or placed with good alignment, and a jam caused by collision between the stacked or placed sheet and a sheet ejected subsequently thereto is prevented, so that a stacking performance or placing performance is not deteriorated.
2. Prior Arts
Conventionally, an apparatus for accumulating and stacking sheets, on which images are formed in an image forming apparatus, such as a copier and printer, has been known. It is needless to say that the apparatus of this type can stack image-formed sheets in a relatively large amount, and also in the apparatus, right before stacking, the sheets ejected from the image forming apparatus are temporarily placed. A predetermined process, such as aligning sheets, stapling, and sorting by sheet shift, is made to the sheets in the temporarily placed condition, and then after the process, the sheets are stacked.
As described above, among apparatuses for stacking sheets, or for stacking sheets after sheets are temporarily placed and predetermined process is made to the sheets before stacking, the apparatuses which have comparatively achieved the miniaturization are disclosed in U.S. Pat. No. 5,021,837, U.S. Pat. No. 5,137,265, and U.S. Pat. No. 5,385,340.
In the disclosed apparatuses, however, sufficient considerations are not made for improving a stacking ability in case of stacking the sheets, or improving a sheet placement performance in case of temporarily placing the sheets before stacking.
Namely, the already stacked or placed sheet may abut against a forward end of a sheet subsequently sent to cause a jam, or a subsequently sent sheet may be stacked on the stacked or placed sheet in a curled condition so that sheets in the folded condition are stacked or placed. Thus, without reaching an amount of stacking or placing set in advance, it is determined that stacking or placing comes to the limit even though the amount is a few, so that the apparatus must be stopped.
To solve the above problem, a height difference between an ejection port for sheets and a support surface for receiving the sheets should be sufficiently large. However, in this case, when the forward end of the ejected sheet is ejected in a downward curl in a sheet support surface side, the sheet in a downward curl on the support surface is ejected as it is, so that the sheet is folded and then stacked or placed, resulting in causing the same problem as mentioned above.
An object of the invention is to provide a sheet receiving apparatus, which prevents an unnecessary abutment between the stacked sheet and the subsequently ejected sheet, or placing or stacking the sheets in a curled condition in case of stacking the ejected sheets, to thereby improve the performance for stacking the sheets.
Another object of the invention is to provide a sheet receiving apparatus, wherein in order to conduct a predetermined process to the sheet before the sheet is ejected to an outside of the apparatus, even in case of temporarily placing the sheets, a jam caused by collision between the placed sheet and the subsequent sheet is prevented, and the performance of placing the sheet for enabling to securely place the predetermined number of sheets temporarily can be secured.
Still another object of the invention is to provide a sheet receiving apparatus, which can stack or place the sheets by precisely aligning the sheets, and at the same time, which is miniaturized and light-weighed as a whole.
To achieve the above objects, a sheet receiving apparatus of the invention is formed of ejecting means for ejecting a sheet to a piling stacker in order to stack the sheets; a sheet placing surface of the piling stacker, which places the sheet ejected along the sheet ejecting direction from the ejecting means and is inclined to be higher toward an upstream side of the ejecting direction, wherein the sheet placing surface is formed of a first sheet placing surface for placing the sheet with a first angle formed by the sheet ejecting direction and the sheet placing surface, and a second sheet placing surface, which places the sheet thereon and is set at an angle larger than the first angle at an upper stream side of the ejecting direction than a position where the first sheet placing surface intersects the sheet ejecting direction; and sheet pressing means which presses the sheet against the second sheet placing surface and is moved by driving means, such as a solenoid.
Also, the sheet pressing means is arranged to project and retract every time the sheet is ejected from a sheet end regulating member side for regulating movement of the sheet in the condition that the sheet is placed on the placing surface, and a timing of projecting and retracting is operated by sheet rear end detecting means located at an upstream side of the ejecting means.
In the sheet receiving apparatus of the invention, also, in order to apply the predetermined processes, such as aligning and binding, to the sheets, before the sheets are completely ejected to the piling stacker, the sheets are temporarily placed on a temporary placing tray located at the upstream side of the sheet ejecting direction. In order to improve an accuracy for aligning and a performance of placing the sheets on the temporary placing tray, sheet transferring means for transferring the sheets on the temporary placing tray is formed of a ring-shaped member flexibly deforming in a thickness direction of the sheets on the temporary placing tray and a crossing direction, respectively, or a transferring unit in which the ring-shaped member is extended between a driving pulley and a driven pulley and which can move in the sheet thickness direction. Also, there is provided aligning means for pressing the sheets, which are transferred onto the temporary placing tray by the transferring means, from the sheet width direction to thereby align the sheets. Then, a positional relationship between the sheet transferring means and the aligning means is structured such that the aligning means regulates a side rim of the sheet at a position where the sheet transferring means contacts the sheet. Incidentally, the arrangement relation, in which the sheet transferring means and the aligning means are overlapped as seen from a direction of the section, contributes to making the apparatus compact.
Further, in order to improve the sheet placing performance in the temporary placing tray, the sheet receiving apparatus of the invention is provided with the sheet pressing means which approaches the upper surface on the temporary placing tray in accordance with the direction of transferring the sheets transferred on the temporary placing tray by the sheet transferring means, and the sheet pressing means is structured to increase the pressing force against the placed sheets in accordance with an increase of the sheets placed on the temporary placing tray.
Further objects and features of the invention will be apparent from the following detail description of the invention with reference to the attached drawings.